The invention relates to the construction of paperboard cartons for dispensing rolls of plastic film, foil, wax paper, etc. More specifically, the invention relates to paperboard cartons having a plastic cutting blade (e.g. polystyrene), and methods of constructing such cartons and attaching the plastic cutting blades to such cartons.
The invention was developed during ongoing developmental efforts by the Assignee of the present application to improve the manufacturing and performance of paperboard dispensing cartons having plastic cutting blades. Copending U.S. patent application Ser. No. 09/471,818, filed on Dec. 22, 1999 entitled xe2x80x9cPaperboard Dispenser Carton with Plastic Cutting Bladexe2x80x9d, by Phillip L. Passamoni, incorporated herein by reference, is an example of a paperboard dispenser carton having a plastic cutting blade developed by the Assignee. As mentioned in the copending patent application, it is well know to dispense plastic film, wax paper, aluminum foil, and other rolls of film web material from a paperboard carton. Normally, paperboard cartons are formed from die-cut paperboard blanks that are glued and folded to form an elongated roll storage cavity. A lid is connected to the carton along a fold line between a back panel of the carton and the lid, such that the lid pivots about the fold line between an open position and a closed position. The lid normally has a front lip that nests adjacent a front panel of the carton when the carton is closed. Alternatively, the lid has a flap that folds inside the front panel to close the carton.
In most conventional paperboard cartons, a serrated metal cutting blade is provided to cut the film or foil. The metal cutting blade is typically attached on the outside surface of the front panel of the carton along the top edge of the front panel, although it is known in the art to attach the metal strip to the inside surface of the front lip on the lid, or on the outside surface of the bottom panel along the front edge of the bottom panel. In each of these arrangements, the serrated edge extends slightly beyond the paperboard panel to which it is attached, thus allowing the user to tear the web with the serrated edge.
The serrated metal cutting blades are typically attached to the paperboard carton by stamping the serrated metal blade onto the paperboard carton blank at a plurality of points. Such stamping techniques have been found much more reliable than adhesive, especially inasmuch as the width of the metal strips is typically about xe2x85x9c of an inch and thus provides insufficient surface area for effective use of adhesive. In most current arrangements, the exposed serrated edge of the metal cutting blade is covered by a removable paperboard closing strip during shipment and handling. The removable paperboard closing strip is a removable extension of the front lip of the carton lid, which is attached along a perforation line. Removable paperboard closing strips are normally adhered to scored targets on the outside surface of the front panel of the carton, although other configurations are possible. The removable closing strips are removed in order to pen the carton for use.
The present invention, as well as the invention disclosed in the above incorporated copending patent application Ser. No. 09/471,818, was developed in an attempt to increase production speeds above those now possible for paperboard cartons using metal cutting blades. The use of plastic cutting blades not only increases production speeds, but the use of plastic cutting blades also simplifies the recycling of paperboard cartons. Metal cutting blades complicate pulping procedures when paperboard cartons are recycled in a batch along with other paper products. For example, it is normally necessary to remove metal cutting blades prior to or during the pulping process in order to protect recycling equipment. The use of plastic cutting blades eliminates this problem. Another advantage of using plastic cutting blades is that the plastic cutting blades are somewhat safer to handle during the manufacturing process, as well as for the end user. In addition, plastic cutting blades generate static when the web is torn and this helps the film stick to the front of the carton. Thus, making it is easier for the user to grab the web for the next tear. Many paperboard cartons using metal cutting blades use a small sticker on the front panel to accomplish the same result.
For the foregoing reasons, it is been found desirable to develop paperboard dispenser cartons having plastic cutting blades.
The invention is a paperboard carton that uses a plastic cutting blade mounted to an inside surface of a panel on the body of the carton. A serrated edge of the plastic cutting blade is exposed to facilitate tearing of a section of web material from a roll contained in the carton. Preferably, exposure of the serrated edge of the plastic cutting blade is accomplished by providing a longitudinal slot in the paperboard carton through which the serrated edge of the plastic cutting blade protrudes slightly. The cutting blade is preferably die cut from a sheet of polystyrene having a thickness of approximately {fraction (20/1000)} of an inch. Each end of the cutting blade preferably contains aggressive teeth, which are larger in size than the remaining teeth of the serrated edge, in order to help initiate tearing of the web material.
In one embodiment of the invention, the longitudinal plastic cutting blade is attached to an inside surface of the front wall of the container such that the serrated edge of the longitudinal cutting blade extends beyond an upper longitudinal edge of the front wall. In this embodiment, the carton preferably includes a longitudinal front flap which is connected to the front wall panel along a scored fold line. The longitudinal front flap folds inward and over the plastic cutting blade. A longitudinal slot is provided along the fold line at the upper longitudinal edge of the front wall. The serrated edge of the cutting blade protrudes through the longitudinal slot, thus allowing the serrated edge of the cutting blade to be exposed for tearing web material from the roll.
In another embodiment of the invention, a longitudinal slot is provided along the fold line between the bottom wall and the front wall of the carton. The longitudinal plastic cutting blade is attached to the inside surface of the bottom wall such that the serrated edge of the plastic cutting blade protrudes slightly through the slot so that the serrated edge is exposed along the lower front edge of the carton between the bottom wall and the front wall panel.
One of the primary advantages of the invention is that the plastic cutting blade can be securely applied to paperboard cartons at a much faster production rate (e.g. approximately 150 units per minute) than the stamped metal cutting blades of the prior art. The plastic cutting blade is preferably attached to the paperboard carton blanks using commercially available print finishing systems in which a feeding mechanism has been modified to accommodate feeding of the elongated plastic cutting blades. Hot melt adhesive is preferably used to secure the plastic cutting blade to the inside surface of the paperboard carton at the appropriate location. It has been found that the use of hot melt adhesive is particularly well suited for high production speeds. At reduced speeds, however, other means of adhering the plastic cutting blade to the paperboard carton may be suitable (e.g. heat sealing, ultrasonic sealing, providing pressure sensitive adhesive on the back of the cutting blade, etc). In order to assure adhesion of the plastic cutting blade to the inside surface of the carton, as well as assure the structural integrity of the plastic cutting blade, the width of the longitudinal cutting blade should be substantial, e.g., approximately 1 inch.
Other advantages and objects of the invention may be apparent to those skilled in the art upon inspecting the following drawings and description thereof.